This invention relates to a mechanical motion-snubbing device or mechanical shock arrestor which is disposed between a supporting member and a supported member to suppress the accelerated displacement of the supported member relative to the supporting structure.
Supported members, for example, pipes built in various plants like chemical plants, steam power plants, and atomic power plants are permitted to be slowly displaced due to, for example, temperature changes. However, it is necessary to protect these pipes from accelerated displacement, particularly vibrations resulting from, for example, earthquakes or any other sudden external shocks. To this end, therefore, pipes are generally securely held on supporting members such as plant structures by means of a mechanical motion-snubbing device.
Such mechanical motion-snubbing devices known to date include a spring type using a buffer spring, oil pressure-actuated type, and friction brake type.
Even when a supported member, for example, a pipe is displaced slowly, the spring type snubbing device applies a reactionary force corresponding to said displacement on the pipe, undesirably increasing the internal stresses of the pipe body itself.
With the oil pressure type snubbing device, it is necessary to periodically replace operation oil due to its relatively early deterioration, and nonmetal parts such as packings due to their low durability. Particularly where the snubbing device is set in an area contaminated by high energy radiation, the difficulties arise that the above-mentioned operation oil and nonmetal parts more noticeably lose their functions.
To resolve such drawbacks, a friction brake type snubbing device has been proposed which consists of a capstan spring combined with an inertia mass (U.S. Pat. No. 3,876,040). This proposed friction brake type snubbing device indeed has considerably great advantages over the aforesaid two types of snubbing devices. But said friction brake type snubbing device is disadvantageous in that the device has a complicated arrangement and is relatively expensive. Further, the following problems are raised with the proposed friction brake type snubbing device. This known snubbing device makes a nonlinear response to the acceleration of external shocks and presents great difficulties in accurately analyzing the displacements or vibrations of pipes or the earthquakeproof property thereof, thus failing to ensure the safety of pipes.
It is accordingly the object of this invention to provide a compact, highly durable, mechanical motion-snubbing device or mechanical shock arrestor of simple arrangement and light weight, free from material liable to be deteriorated by high energy radiation, saved from the occurrence of resonance, and further capable of accurately analyzing the earthquakeproof property of supported members, for example, pipes, effectively suppressing their displacements or vibrations and consequently well adapted to be used therewith.